Electron beam techniques were used to characterize uranium-contaminated soils at the Fernald site in Ohio. Uranium particulates had been deposited on the soil through chemical spills and from the operation of an incinerator plant on the site. The major uranium phases were identified using analytical electron microscopy (AEM) combined with electron diffraction as uranyl phosphate (meta-autunite), uranium oxide (uraninite), and uranium metaphosphate [U(PO3)4]. The U(PO3)4 was found predominantly at an incinerator site at Fernald. Carbonate leaching in an oxygen environment has removed some of the U(IV) phases; however, U(PO3)4 has not been removed by any of the chemical remediation technologies tried to date. These observations suggest that an additional physical extraction procedure is needed to remove this phase. Some evidence suggests that the uranium has undergone weathering, resulting in its redistribution within the soil.

No abstract

Metabotropic glutamate receptors (mGluRs) in the medulla oblongata have been suggested to be involved in the regulation of autonomic function. The aim of the present study was to examine the localization and expression of four types of mGluRs: mGluRla, mGluR2/3, mGluR5, and mGluR7 in the dorsal and ventral autonomic nuclei of the medulla of the rat. The four mGluR subtypes studied were differentially distributed in distinct subnuclei in the nucleus of the solitary tract (NTS). mGluRla immunoreactivity was identified in cell bodies, dendrites, and axonal processes in the intermediate, dorsal lateral, and interstitial subnuclei of the NTS. No mGluRla immunoreactivity was observed in the commissural or medial NTS subnuclei. Immunoreactivity for mGluR2/3 and mGluR5 as observed in fibers and putative axonal processes in the interstitial, intermediate, and dorsolateral subnuclei of the NTS. In contrast, mGluR7 was expressed primarily in fibers and terminals in the central and commissural NTS subnuclei. Expression of mGluR2/3 was clearly evident in cell bodies, dendrites, and axonal processes within the area postrema. The vagal outflow nuclei were also studied. The dorsal motor nucleus of the vagus (DMN) contained mGluRla cell bodies, dendrites, and axonal fibers and light mGluR2/3 processes. Throughout the rostral-caudal extent of the compact and semicompact formation nucleus ambiguus, mGluRla was found in cell bodies and fibers. Within the caudal and rostral regions of the ventral lateral medulla, mGluRla was observed in cell bodies and fibers. Cell bodies containing mGluRla were found adjacent to cells staining positive for tyrosine hydroxylase (TH) in these regions but were not colocalized with the TH staining. However, mGluRla-expressing neurons in the ventral lateral medulla did appear to receive innervation from TH-containing fibers. These results suggest that the mGluRla-expressing neurons within the ventral lateral medulla are predominantly not catecholaminergic but may be innervated by catecholamine-containing fibers. These data are the first to provide a mapping of the different mGluR subtypes within the medulla and may facilitate predictions regarding the function of L-glutamate neurotransmission in these regions.

A program has been established for DOE Environmental Restoration and Waste Management (EM) to evaluate factors that are likely to affect waste glass reaction ,during repository disposal, with emphasis on an unsaturated environment typical of what may be expected for the proposed Yucca Mountain repository site. This report covers progress in FY 1991 on the following tasks: 11 A critic_ review of those parameters that affect the reactivity of glass in an unsaturated environment is in progress. This effort involves a search of the literature to identify the important parameters. Temperature and glass compositions are the first parameters examined in detail. 2, An interface between waste producers and the repository program is being implemented. 3. A series of tests has been started to evaluate the reactivity of fully radioactive glasses in a high-level waste repository environment mad compare it to the reactivity of synthetic glasses of similar composition. 4. The effect of radiation upon the durability of waste glasses at a high glass surface. _ea-tc)-liquid volume fSA/V) _ttio m3d higl_ gas-to-liquid volume ratio will be assessed. These tesLsaddress both vapor m_d high SA/V liquid conditions. 5. A series of test:_ is being performed to compare the extent of reaction (_t" nuclear waste glasses at various SA/V ratios, Such differences in the SA/V ratio may significantly affect glass durability. 6. An_ytical electron microscopy (AEM), infrared spectroscopy, and nuclear : resonant profiling are being used to assess the glass/water reaction pathway by identil'ying intermediate phases that appear on the reacting glass. Additionally, colloids trom the leach solutions are being studied using AEM.

Characterization of the actinide content of a sample of contaminated coral soil from Johnston Atoll, the site of three non-nuclear destructs of nuclear warhead-carrying THOR missiles in 1962, revealed that >99% of the total actinide content is associated with discrete bomb fragments. After removal of these fragments, there was an inverse correlation between actinide content and soil particle size in particles from 43 to 0.4 µm diameter. Detailed analyses of this remaining soil revealed no discrete actinide phase in these soil particles, despite measurable actinide content. Observations indicate that exposure to the environment has caused the conversion of relatively insoluble actinide oxides to the more soluble actinyl oxides and actinyl carbonate coordinated complexes. This process has led to dissolution of actinides from discrete particles and migration to the surrounding soil surfaces, resulting in a dispersion greater than would be expected by physical transport of discrete particles alone.